Implantable cardiac devices typically sense cardiac electrical signals in an implantee and classify the implantee's cardiac rhythm as normal/benign or treatable/malignant. Illustrative malignant rhythms may include ventricular fibrillation and/or polymorphic ventricular tachyarrhythmia. Other rhythms may also be considered malignant or treatable, such as bradycardia or monomorphic tachyarrhythmia. The accuracy with which an implantable medical device analyzes sensed signals determines how well it makes therapy determinations and other decisions.
New and/or alternative methods and devices for cardiac signal analysis are desired.